使用XmlWriter附加现有XML文件

终于我成功了:)

if (!File.Exists("Test.xml")){   XmlWriterSettings xmlWriterSettings = new XmlWriterSettings();   xmlWriterSettings.Indent = true;   xmlWriterSettings.newlineonAttributes = true;   using (XmlWriter xmlWriter = XmlWriter.Create("Test.xml", xmlWriterSettings))   {      xmlWriter.WriteStartdocument();      xmlWriter.WriteStartElement("School");      xmlWriter.WriteStartElement("Student");      xmlWriter.WriteElementString("FirstName", firstName);      xmlWriter.WriteElementString("LastName", lastName);      xmlWriter.WriteEndElement();      xmlWriter.WriteEndElement();      xmlWriter.WriteEnddocument();      xmlWriter.Flush();      xmlWriter.Close();   }}else{   Xdocument xdocument = Xdocument.Load("Test.xml");   XElement root= xdocument.Element("School");   IEnumerable<XElement> rows = root.Descendants("Student");   XElement firstRow= rows.First();   firstRow.AddBeforeSelf(      new XElement("Student",      new XElement("FirstName", firstName),      new XElement("LastName", lastName)));   xdocument.Save("Test.xml");}